Vehicle and method of preconditioning cabin air within a vehicle

ABSTRACT

A vehicle includes a climate control system, an engine, a battery, and a controller. The engine and the battery are each configured to power the climate control system. The controller is programmed to, responsive to a request to precondition cabin air and an estimated battery state of charge, that would result from the climate control system preconditioning the air, being less than a threshold, start the engine to power the climate control system regardless of an initial battery state of charge.

TECHNICAL FIELD

The present disclosure relates to vehicles and control systems to condition cabin air within a vehicle.

BACKGROUND

Vehicles may include climate control systems that are configured to control the temperature of the air within the vehicle cabin.

SUMMARY

A vehicle includes a climate control system, an engine, a battery, and a controller. The engine and the battery are each configured to power the climate control system. The controller is programmed to, responsive to a request to precondition cabin air and an estimated battery state of charge, that would result from the climate control system preconditioning the air, being less than a threshold, start the engine to power the climate control system regardless of an initial battery state of charge.

A method includes starting an engine to power a climate control system regardless of an initial battery state of charge responsive to a request to precondition vehicle cabin air to a target temperature via a climate control system and an estimated battery state of charge, that would result from powering the climate control system to adjust the cabin air from an initial temperature to the target temperature, being less than a threshold.

A vehicle includes an engine, a battery, a climate control system, and a controller. The engine and the battery are each configured to power the climate control system. The controller is programmed to, responsive to a command to precondition cabin air and an estimated battery state of charge, that would result from operating the climate control system to achieve the precondition, being less than a threshold, start the engine to power the climate control system regardless of an initial battery state of charge. The controller is further programmed to, responsive to the command and the estimated battery state of charge exceeding the threshold, power the climate control system via the battery while the engine remains shutdown.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an exemplary powertrain of a hybrid electric vehicle;

FIG. 2 is a schematic illustration of a climate control system of the vehicle; and

FIG. 3 is a flowchart illustrating a method of preconditioning cabin air.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.

Referring to FIG. 1, a schematic diagram of a hybrid electric vehicle (HEV) 10 is illustrated according to an embodiment of the present disclosure. FIG. 1 illustrates representative relationships among the components. Physical placement and orientation of the components within the vehicle may vary. The HEV 10 includes a powertrain 12. The powertrain 12 includes an engine 14 that drives a transmission 16, which may be referred to as a modular hybrid transmission (MHT). As will be described in further detail below, transmission 16 includes an electric machine such as an electric motor/generator (M/G) 18, an associated traction battery 20, a torque converter 22, and a multiple step-ratio automatic transmission, or gearbox 24.

The engine 14 and the M/G 18 are both drive sources for the HEV 10 that are configured to propel the HEV 10. The engine 14 generally represents a power source that may include an internal combustion engine such as a gasoline, diesel, or natural gas powered engine, or a fuel cell. The engine 14 generates an engine power and corresponding engine torque that is supplied to the M/G 18 when a disconnect clutch 26 between the engine 14 and the M/G 18 is at least partially engaged. The M/G 18 may be implemented by any one of a plurality of types of electric machines. For example, M/G 18 may be a permanent magnet synchronous motor. Power electronics condition direct current (DC) power provided by the battery 20 to the requirements of the M/G 18, as will be described below. For example, power electronics may provide three phase alternating current (AC) to the M/G 18.

When the disconnect clutch 26 is at least partially engaged, power flow from the engine 14 to the M/G 18 or from the M/G 18 to the engine 14 is possible. For example, the disconnect clutch 26 may be engaged and M/G 18 may operate as a generator to convert rotational energy provided by a crankshaft 28 and M/G shaft 30 into electrical energy to be stored in the battery 20. The disconnect clutch 26 can also be disengaged to isolate the engine 14 from the remainder of the powertrain 12 such that the M/G 18 can act as the sole drive source for the HEV 10. Shaft 30 extends through the M/G 18. The M/G 18 is continuously drivably connected to the shaft 30, whereas the engine 14 is drivably connected to the shaft 30 only when the disconnect clutch 26 is at least partially engaged.

The M/G 18 is connected to the torque converter 22 via shaft 30. The torque converter 22 is therefore connected to the engine 14 when the disconnect clutch 26 is at least partially engaged. The torque converter 22 includes an impeller fixed to M/G shaft 30 and a turbine fixed to a transmission input shaft 32. The torque converter 22 thus provides a hydraulic coupling between shaft 30 and transmission input shaft 32. The torque converter 22 transmits power from the impeller to the turbine when the impeller rotates faster than the turbine. The magnitude of the turbine torque and impeller torque generally depend upon the relative speeds. When the ratio of impeller speed to turbine speed is sufficiently high, the turbine torque is a multiple of the impeller torque. A torque converter bypass clutch (also known as a torque converter lock-up clutch) 34 may also be provided that, when engaged, frictionally or mechanically couples the impeller and the turbine of the torque converter 22, permitting more efficient power transfer. The torque converter bypass clutch 34 may be operated as a launch clutch to provide smooth vehicle launch. Alternatively, or in combination, a launch clutch similar to disconnect clutch 26 may be provided between the M/G 18 and gearbox 24 for applications that do not include a torque converter 22 or a torque converter bypass clutch 34. In some applications, disconnect clutch 26 is generally referred to as an upstream clutch and launch clutch 34 (which may be a torque converter bypass clutch) is generally referred to as a downstream clutch.

The gearbox 24 may include gear sets (not shown) that are selectively placed in different gear ratios by selective engagement of friction elements such as clutches and brakes (not shown) to establish the desired multiple discrete or step drive ratios. The friction elements are controllable through a shift schedule that connects and disconnects certain elements of the gear sets to control the ratio between a transmission output shaft 36 and the transmission input shaft 32. The gearbox 24 is automatically shifted from one ratio to another based on various vehicle and ambient operating conditions by an associated controller, such as a powertrain control unit (PCU). Power and torque from both the engine 14 and the M/G 18 may be delivered to and received by gearbox 24. The gearbox 24 then provides powertrain output power and torque to output shaft 36.

It should be understood that the hydraulically controlled gearbox 24 used with a torque converter 22 is but one example of a gearbox or transmission arrangement; any multiple ratio gearbox that accepts input torque(s) from an engine and/or a motor and then provides torque to an output shaft at the different ratios is acceptable for use with embodiments of the present disclosure. For example, gearbox 24 may be implemented by an automated mechanical (or manual) transmission (AMT) that includes one or more servo motors to translate/rotate shift forks along a shift rail to select a desired gear ratio. As generally understood by those of ordinary skill in the art, an AMT may be used in applications with higher torque requirements, for example.

As shown in the representative embodiment of FIG. 1, the output shaft 36 is connected to a differential 40. The differential 40 drives a pair of wheels 42 via respective axles 44 connected to the differential 40. The differential transmits approximately equal torque to each wheel 42 while permitting slight speed differences such as when the vehicle turns a corner. Different types of differentials or similar devices may be used to distribute torque from the powertrain to one or more wheels. In some applications, torque distribution may vary depending on the particular operating mode or condition, for example.

The powertrain 12 further includes an associated controller 50 such as a powertrain control unit (PCU). While illustrated as one controller, the controller 50 may be part of a larger control system and may be controlled by various other controllers throughout the vehicle 10, such as a vehicle system controller (VSC). It should therefore be understood that the powertrain control unit 50 and one or more other controllers can collectively be referred to as a “controller” that controls various actuators in response to signals from various sensors to control functions such as starting/stopping engine 14, operating M/G 18 to provide wheel torque or charge battery 20, select or schedule transmission shifts, etc. Controller 50 may include a microprocessor or central processing unit (CPU) in communication with various types of computer readable storage devices or media. Computer readable storage devices or media may include volatile and nonvolatile storage in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM), for example. KAM is a persistent or non-volatile memory that may be used to store various operating variables while the CPU is powered down. Computer-readable storage devices or media may be implemented using any of a number of known memory devices such as PROMs (programmable read-only memory), EPROMs (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or any other electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions, used by the controller in controlling the engine or vehicle.

The controller communicates with various engine/vehicle sensors and actuators via an input/output (I/O) interface (including input and output channels) that may be implemented as a single integrated interface that provides various raw data or signal conditioning, processing, and/or conversion, short-circuit protection, and the like. Alternatively, one or more dedicated hardware or firmware chips may be used to condition and process particular signals before being supplied to the CPU. As generally illustrated in the representative embodiment of FIG. 1, controller 50 may communicate signals to and/or from engine 14, disconnect clutch 26, M/G 18, battery 20, launch clutch 34, transmission gearbox 24, and power electronics 56. Although not explicitly illustrated, those of ordinary skill in the art will recognize various functions or components that may be controlled by controller 50 within each of the subsystems identified above. Representative examples of parameters, systems, and/or components that may be directly or indirectly actuated using control logic and/or algorithms executed by the controller include fuel injection timing, rate, and duration, throttle valve position, spark plug ignition timing (for spark-ignition engines), intake/exhaust valve timing and duration, front-end accessory drive (FEAD) components such as an alternator, air conditioning compressor, battery charging or discharging (including determining the maximum charge and discharge power limits), regenerative braking, M/G operation, clutch pressures for disconnect clutch 26, launch clutch 34, and transmission gearbox 24, and the like. Sensors communicating input through the I/O interface may be used to indicate turbocharger boost pressure, crankshaft position (PIP), engine rotational speed (RPM), wheel speeds (WS1, WS2), vehicle speed (VSS), coolant temperature (ECT), intake manifold pressure (MAP), accelerator pedal position (PPS), ignition switch position (IGN), throttle valve position (TP), air temperature (TMP), exhaust gas oxygen (EGO) or other exhaust gas component concentration or presence, intake air flow (MAF), transmission gear, ratio, or mode, transmission oil temperature (TOT), transmission turbine speed (TS), torque converter bypass clutch 34 status (TCC), deceleration or shift mode (MDE), battery temperature, voltage, current, or state of charge (SOC) for example.

Control logic or functions performed by controller 50 may be represented by flow charts or similar diagrams in one or more figures. These figures provide representative control strategies and/or logic that may be implemented using one or more processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various steps or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Although not always explicitly illustrated, one of ordinary skill in the art will recognize that one or more of the illustrated steps or functions may be repeatedly performed depending upon the particular processing strategy being used. Similarly, the order of processing is not necessarily required to achieve the features and advantages described herein, but is provided for ease of illustration and description. The control logic may be implemented primarily in software executed by a microprocessor-based vehicle, engine, and/or powertrain controller, such as controller 50. Of course, the control logic may be implemented in software, hardware, or a combination of software and hardware in one or more controllers depending upon the particular application. When implemented in software, the control logic may be provided in one or more computer-readable storage devices or media having stored data representing code or instructions executed by a computer to control the vehicle or its subsystems. The computer-readable storage devices or media may include one or more of a number of known physical devices which utilize electric, magnetic, and/or optical storage to keep executable instructions and associated calibration information, operating variables, and the like.

An accelerator pedal 52 is used by the driver of the vehicle to provide a demanded torque, power, or drive command to propel the vehicle. In general, depressing and releasing the accelerator pedal 52 generates an accelerator pedal position signal that may be interpreted by the controller 50 as a demand for increased power or decreased power, respectively. A brake pedal 58 is also used by the driver of the vehicle to provide a demanded braking torque to slow the vehicle. In general, depressing and releasing the brake pedal 58 generates a brake pedal position signal that may be interpreted by the controller 50 as a demand to decrease the vehicle speed. Based upon inputs from the accelerator pedal 52 and brake pedal 58, the controller 50 commands the torque to the engine 14, M/G 18, and friction brakes 60. The controller 50 also controls the timing of gear shifts within the gearbox 24, as well as engagement or disengagement of the disconnect clutch 26 and the torque converter bypass clutch 34. Like the disconnect clutch 26, the torque converter bypass clutch 34 can be modulated across a range between the engaged and disengaged positions. This produces a variable slip in the torque converter 22 in addition to the variable slip produced by the hydrodynamic coupling between the impeller and the turbine. Alternatively, the torque converter bypass clutch 34 may be operated as locked or open without using a modulated operating mode depending on the particular application.

To drive the vehicle with the engine 14, the disconnect clutch 26 is at least partially engaged to transfer at least a portion of the engine torque through the disconnect clutch 26 to the M/G 18, and then from the M/G 18 through the torque converter 22 and gearbox 24. The M/G 18 may assist the engine 14 by providing additional power to turn the shaft 30. This operation mode may be referred to as a “hybrid mode” or an “electric assist mode.”

To drive the vehicle with the M/G 18 as the sole power source, the power flow remains the same except the disconnect clutch 26 isolates the engine 14 from the remainder of the powertrain 12. Combustion in the engine 14 may be disabled or otherwise OFF during this time to conserve fuel. The traction battery 20 transmits stored electrical energy through wiring 54 to power electronics 56 that may include an inverter, for example. The power electronics 56 convert DC voltage from the battery 20 into AC voltage to be used by the M/G 18. The controller 50 commands the power electronics 56 to convert voltage from the battery 20 to an AC voltage provided to the M/G 18 to provide positive or negative torque to the shaft 30. This operation mode may be referred to as an “electric only” or “EV” operation mode.

In any mode of operation, the M/G 18 may act as a motor and provide a driving force for the powertrain 12. Alternatively, the M/G 18 may act as a generator and convert kinetic energy from the powertrain 12 into electric energy to be stored in the battery 20. The M/G 18 may act as a generator while the engine 14 is providing propulsion power for the vehicle 10, for example. The M/G 18 may additionally act as a generator during times of regenerative braking in which torque and rotational (or motive) energy or power from spinning wheels 42 is transferred back through the gearbox 24, torque converter 22, (and/or torque converter bypass clutch 34) and is converted into electrical energy for storage in the battery 20.

The battery 20 and/or the M/G 18 may also be configured to provide electrical power to one or more vehicle accessories 62. The vehicle accessories 62 may include, but are not limited to, climate control systems, power steering systems, electric heaters, or any other system or device that is electrically operated.

An integrated starter-generator (ISG) 64 may be coupled to the engine 14 (i.e., may be coupled to the crankshaft 28 of the engine 14). The ISG 64 may be configured to operate as a motor to start the engine 14 during an engine start-up event, or to provide additional torque to the powertrain 12 during vehicle operations. The ISG 64 may also be configured to receiving torque from the engine 14 and operate as a generator. The ISG 64 may be selectively coupled to the engine by a clutch 66, belt 68, and a pair of pulleys 70. If the ISG 64 is coupled to the engine by a belt 68 it may be referred to as a belt integrated starter-generator (BISG). The controller 50 may be configured to transmit signals to the ISG 64 to operate the ISG 64 as either a motor or a generator. The controller may also be configured to transmit signals to the clutch 66 in order to open or close the clutch 66. The ISG 64 will be coupled to the engine 14 when the clutch is in a closed state and decoupled from the engine 14 when the clutch 66 is in an open state. The ISG 64 may be configured to provide electrical energy to charge an accessory battery 72, the traction battery 20, or provide electrical energy to power the vehicle accessories 62 when operating as a generator. The accessory battery 72 may also be configured to power the vehicle accessories 62.

The vehicle 10 may include an electrical outlet 74 that is configured receive a plug 76 from a charging station 78 in order to establish an electrical connection between the battery 20 and the charging station 78. Once the electrical connection has been established, the charging station 78 is configured to recharge the battery 20.

The controller 50 may be configured to receive various states or conditions of the various vehicle components illustrated in FIG. 1 via electrical signals. The electrical signals may be delivered to the controller 50 from the various components via input channels. Additionally, the electrical signals received from the various components may be indicative of a request or a command to change or alter a state of one or more of the respective components of the vehicle 10. The controller 50 includes output channels that are configured to deliver requests or commands (via electrical signals) to the various vehicle components. The controller 50 includes control logic and/or algorithms that are configured to generate the requests or commands delivered through the output channels based on the requests, commands, conditions, or states of the various vehicle components.

The input channels and output channels are illustrated as dotted lines in FIG. 1. It should be understood that a single dotted line may be representative of both an input channel and an output channel into or out of a single element. Furthermore, an output channel into one element may operate as an input channel to another element and vice versa.

It should be understood that the schematic illustrated in FIG. 1 is merely representative and is not intended to be limiting. Other configurations are contemplated that utilize selective engagement of both an engine and a motor to transmit power through the transmission. For example, the M/G 18 may be offset from the crankshaft 28, and/or the M/G 18 may be provided between the torque converter 22 and the gearbox 24. Other configurations are contemplated without deviating from the scope of the present disclosure.

It should further be understood that the vehicle configuration described herein is merely exemplary and is not intended to be limited. Other hybrid vehicle configurations should be construed as disclosed herein. Other hybrid vehicle configurations may include, but are not limited to series hybrid vehicles, parallel hybrid vehicles, series-parallel hybrid vehicles, plug-in hybrid electric vehicles (PHEVs), fuel cell hybrid vehicles, or any other hybrid vehicle configuration known to a person of ordinary skill in the art.

Referring to FIG. 2, a climate control system 80 of the vehicle 10 is illustrated. The climate control system 80 is configured to condition air that is being introduced into the cabin 82 of the vehicle 10. The climate control system 80 includes a coolant circuit 84 that is configured increase the temperature of the air that is within or is being introduced into the cabin 82. The climate control system 80 also includes a refrigerant circuit 86 that is configured to decrease the temperature of and dry the air that is within or is being introduced into the cabin 82.

The coolant circuit 84 includes a pump 88 that is configured to circulate coolant through the coolant circuit 84, an electric heater 90 (such as a positive temperature coefficient or PTC heater) that is configured to heat the coolant within the coolant circuit 84, and a heat exchanger 92 (e.g., a heater core). A fan 94 is configured to direct air across the heat exchanger 92 in order to heat air that is being directed into the cabin 82 of the vehicle 10. The controller 50 may be configured to operate the pump 88, the electric heater 90, and/or the fan 94 in order to provide heating to the cabin 82 in response to a request from a vehicle operator to increase the air temperature the cabin 82.

The vehicle operator may request cabin heating by communicating with the controller 50 via a human machine interface (HMI) 96. Alternatively, the vehicle operator may request cabin heating by communicating 50 with the controller 50 via a wireless device 98, such as a key fob. The M/G 18, the battery 20, the ISG 64, and the accessory battery 72 may all be configured to provide electrical power to operate the climate control system 80 (e.g., the pump 88, the electric heater 90, and the fan 94) in order to heat the cabin air through various electrical connections (not shown). The engine 14 may power the M/G 18 or the ISG 64 in order to generate the electrical power to operate the climate control system 80 when heating the cabin air.

The coolant circuit 84 may also be configured to direct coolant through passages (not shown) within the engine 14 in order to remove excess heat from the engine 14 that is generated by combustion. The coolant circuit 84 may also include a second heat exchanger (not shown), such as a radiator, that is configured to reject excess heat from the coolant within the coolant circuit 84 to the ambient surroundings (e.g., the ambient air). A second fan (not shown) may be configured to direct air across the second heat exchanger in order reject excess heat from the coolant within the coolant circuit 84 to the ambient surroundings.

The refrigerant circuit 86 includes a refrigerant compressor 100, a condenser 102, an evaporator 104, and a thermal expansion valve 106. The fan 94 may be configured to direct air across the evaporator 104 in order to cool and dry the air that is being directed into the cabin 82. A secondary fan 108 may be configured to direct air across the condenser 100 in order to reject heat from the refrigerant circuit 86 to the ambient surroundings (e.g., the ambient air). The controller 50 may be configured to operate the refrigerant compressor 100, the fan 94, and/or the secondary fan 108 in order to provide cooling to the cabin 82 in response to a request from a vehicle operator to decrease the air temperature the cabin 82.

The vehicle operator may request cabin cooling by communicating with the controller 50 via a human machine interface (HMI) 96. Alternatively, the vehicle operator may request cabin cooling by communicating 50 with the controller via the wireless device 98. The M/G 18, the battery 20, the ISG 64, and the accessory battery 72 may all be configured to provide electrical power to operate the climate control system 80 (e.g., the compressor 100, the fan 94, and the secondary fan 108) in order to cool the cabin air through various electrical connections (not shown). The engine 14 may power the M/G 18 or the ISG 64 in order to generate the electrical power operate the climate control system 80 when cooling the cabin air.

The request to heat or cool the cabin air may be a generic request to condition the cabin air to a target or desired temperature. The controller 50 may then determine to operate either the coolant circuit 84 to heat the cabin air or the refrigerant circuit 86 to cool the cabin air. The coolant circuit may be operated to heat the cabin 82 if the initial or current temperature of the cabin air is less than the desired temperature. The refrigerant circuit 86 may be operated to cool the cabin 82 if the current temperature of the cabin air is greater than the target temperature. A cabin air temperature sensor 110 may be configured to detect and communicate the current temperature of the air within the cabin 82 to the controller 50. An ambient air temperature sensor 112 may be configured to detect and communicate the current temperature of the ambient air surrounding the vehicle 10 to the controller 50.

The request to condition the cabin air may be a request to precondition the air prior to the vehicle operator entering the vehicle and turning on an ignition of the vehicle 10. As previously stated, the request may be made via the HMI 96 or the wireless device 98. The vehicle operator or user may also program the controller 50 (via the HMI 96 or wireless device 98) such that the request to precondition the cabin air to the target air temperature is preset to occur on a specific date, on a specific day of the week, and/or at a specific time of day.

Referring to FIG. 3, a method 200 of preconditioning the air being introduced into the cabin 82 is illustrated. The method 200 may be stored as control logic and/or an algorithm within the controller 50. The controller 50 may implement the method 200 by controlling the various components of the vehicle 10, including the subcomponents of the climate control system 80 depicted in FIG. 2. The method 200 is initiated at block 202, where it is determined if there is a request from the vehicle operator (via the HMI 96 or the wireless device 98) to precondition the cabin air to a target temperature. If there is not a request to precondition the cabin air to a target temperature, the method 200 recycles back to the beginning of block 202. If there is a request to precondition the cabin air to a target temperature, the method moves on to block 204.

At block 204, it is determined if an estimated battery state of charge, that would result from the climate control system 80 preconditioning the cabin air, is less than a threshold regardless of an initial or current state of charge. The estimated battery state of charge is a state charge of the battery 20 that would result if the battery alone 20 were utilized to power the climate control system 80 to precondition the cabin air (i.e., if the battery alone 20 where utilized to power the climate control system 80 to adjust the cabin air temperature from the initial or current temperature to the desired or target temperature). Expressed mathematically, the estimated battery state of charge may be represented by equation (1):

Q _(est) =Q _(int) −ΔQ  (1)

where Q_(est) is the estimated battery state of charge that would result if the battery 20 alone were utilized to power the climate control system 80 to precondition the cabin air, Q_(int) is the initial or current battery state of charge prior to operating the climate control system 80 to precondition the cabin air, and ΔQ the change in the state of charge of the battery 20 that would result if the battery 20 alone were utilized to power the climate control system 80 to precondition the cabin air.

Equation (1) may be adjusted based on a charging condition of the battery 20. For example, if the battery 20 is being recharged via the electrical outlet 74, plug 76, and charging station 78, the estimated battery state of charge that would result if the battery 20 alone were utilized to power the climate control system 80 to precondition the cabin air, Q_(est), may be adjusted to include an estimated received charge that would be introduced via recharging while the climate control system 80 is preconditioning the cabin air. Expressed mathematically, the estimated battery state of charge, Q_(est), may be adjusted to equation (2) to compensate for the charging condition of the battery 20:

Q _(est) =Q _(int) −ΔQ+Q _(charge)  (2)

where Q_(charge) is the estimated received charge that would be introduced via recharging while the climate control system 80 preconditioning the air.

The change in the state of charge of the battery 20 that would result if the battery 20 alone were utilized to power the climate control system 80 to precondition the cabin air (i.e., ΔQ) may be related to an estimated energy required to power the climate control system 80 to precondition the cabin air (i.e., an estimated energy to adjust the temperature of the cabin air from initial or current temperature to the desired or target temperature). Expressed mathematically, the estimated energy required to power the climate control system 80 if the battery 20 alone were utilized to power the climate control system 80 to precondition the cabin air may be represented by equation (3):

E _(precon)=∫_(t) ₀ ^(t) ¹ (V*ΔQ)dt  (3)

where E_(precon) is the estimated energy required to power the climate control system 80 to precondition the cabin air over a period of time from t₀ to t₁ and V is the voltage applied to operate the various devices of the climate control system 80 to precondition the cabin air. If the climate control system 80 is the heating the cabin air, the estimated energy required to power the climate control system to precondition the cabin air, E_(precon), may be the estimated energy required to operate the pump 88, the electric heater 90, and/or the fan 94 in order to increase the temperature of the cabin air from the initial or current temperature to the desired or target temperature (operation of the electric heater 90 may or may not be required depending of the temperature of the coolant within the coolant circuit 84). On the other hand, if the climate control system 80 is the cooling the cabin air, the estimated energy required to power the climate control system to precondition the cabin air, E_(precon), may be the estimated energy required to operate the refrigerant compressor 100, the fan 94, and/or the secondary fan 108 in order to decrease the temperature of the cabin air from initial or current temperature to the desired or target temperature.

The estimated energy required to power the climate control system to precondition the cabin air, E_(precon), may also be represented as a function of difference between the initial or current temperature and the desired or target temperature minus any thermal or heat losses to the ambient surroundings. Expressed mathematically, the estimated energy required to power the climate control system to precondition the cabin air, E_(precon), may also be represented by equation (4):

E _(precon) =f(T _(int) −T _(target))−H _(loss)  (4)

where T_(int) is initial or current temperature of the cabin air, T_(target) is the desired or target temperature of the cabin air, and H_(loss) are the thermal or heat losses to the ambient surroundings. In alternative embodiment, the initial or current temperature T_(int) may be replaced in equation (4) by the ambient air temperature. This may be advantageous under circumstances where air from the ambient surroundings (as opposed to air that is being recirculated within the cabin) is being conditioned and introduced into the cabin 82. When the air is being recirculated within the cabin, the current temperature of the cabin T_(int) should be utilized in equation (4). Alternatively, the estimated energy required to power the climate control system to precondition the cabin air, E_(precon), could be a look table that relates the estimated energy required to power the climate control system to precondition the cabin air, E_(precon), to the initial or current temperature of the cabin air, T_(int), the ambient air temperature, and/or the desired or target temperature of the cabin air, T_(target). The lookup tables may be based previously recorded data.

Based on the relationships between equations (1)-(4), the estimated battery state of charge that would result if the battery 20 alone were utilized to power the climate control system 80 to precondition the cabin air, Q_(est), may be adjusted such that it is based on the estimated energy required to power the climate control system 80 to precondition the cabin air, E_(precon), (i.e., the estimated energy to adjust the temperature of the cabin air from initial or current temperature, T_(int), to the desired or target temperature, T_(target)).

If it is determined at block 204 that the estimated battery state of charge, that would result from the climate control system 80 preconditioning the air, Q_(est), is less than the threshold, regardless of the initial or current state of charge, Q_(int), the method 200 moves on to block 206 where the engine 14 is started to power the climate control system 80 in order to precondition the cabin air. More specifically, the engine 14 may operate the ISG 64 and/or the M/G 18 to provide electrical power to the various subcomponents of the climate control system 80 depicted in FIG. 2 (e.g., the pump 88, the electric heater 90, the fan 94, the refrigerant compressor 100, and/or the secondary fan 108) to precondition the cabin air. The engine 14 may power the climate control system 80 alone at block 206. Alternatively, the engine 14 and the battery 20 may both power the climate control system 80 at block 206, where the power utilized by the battery 20 is limited such that state of charge of the battery 20 remains above the threshold referenced in block 204 when the preconditioning of the cabin air is completed.

Returning to block 204, if it is determined that the estimated battery state of charge, that would result from the climate control system 80 preconditioning the air, Q_(est), is greater than the threshold, regardless of an initial or current state of charge, Q_(int), the method 200 moves on to block 208, where the battery 20 alone is utilized to power the climate control system 80 to precondition the cabin air. More specifically, the battery may provide electrical power to the various subcomponents of the climate control system 80 depicted in FIG. 2 (e.g., the pump 88, the electric heater 90, the fan 94, the refrigerant compressor 100, and/or the secondary fan 108) to precondition the cabin air. The engine 14 remains shutdown at block 208 or is specifically commanded to remain shutdown via the controller 50 at block 208. It should be understood that the flowchart in FIG. 3 is for illustrative purposes only and that the method 200 should not be construed as limited to the flowchart in FIG. 3. Some of the steps of the method 200 may be rearranged while others may be omitted entirely.

The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form further embodiments that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications. 

What is claimed is:
 1. A vehicle comprising: a climate control system; an engine and a battery, each configured to power the climate control system; and a controller programmed to, responsive to a request to precondition cabin air and an estimated battery state of charge, that would result from the climate control system preconditioning the air, being less than a threshold, start the engine to power the climate control system regardless of an initial battery state of charge.
 2. The vehicle of claim 1, wherein the controller is further programmed to, responsive to the request and the estimated battery state of charge exceeding the threshold, command the engine to remain shutdown and power the climate control system via the battery.
 3. The vehicle of claim 1, wherein the estimated battery state of charge is based on an estimated energy output required to power the climate control system to adjust a cabin air temperature from an initial temperature to a target temperature.
 4. The vehicle of claim 3, wherein the estimated energy output is adjusted to compensate for thermal losses to ambient surroundings.
 5. The vehicle of claim 1 further comprising an electrical connector configured to mate with and receive electrical power from a charging station to recharge the battery, and wherein the estimated battery state of charge is adjusted based on a battery charging condition.
 6. The vehicle of claim 1, wherein the request to precondition cabin air is triggered by a user presetting of a target cabin air temperature at a specific time of day.
 7. The vehicle of claim 1, wherein the request to precondition cabin air is triggered by a wireless device.
 8. A method comprising: responsive to a request to precondition a vehicle cabin air to a target temperature via a climate control system and an estimated battery state of charge, that would result from powering the climate control system to adjust the cabin air from an initial temperature to the target temperature, being less than a threshold, starting an engine to power the climate control system regardless of an initial battery state of charge.
 9. The method of claim 8 further comprising: responsive to the request and the estimated battery state of charge exceeding the threshold, commanding the engine to remain shutdown and powering the climate control system via the battery.
 10. The method of claim 8, wherein the estimated battery state of charge is based on an estimated energy output required to power the climate control system to adjust the cabin air from the initial temperature to the target temperature.
 11. The method of claim 10, wherein the estimated energy output is adjusted to compensate for thermal losses to ambient surroundings.
 12. The method of claim 8, wherein the estimated battery state of charge is adjusted based on a battery charging condition.
 13. The method of claim 8, wherein the request to precondition the cabin air is triggered by a user presetting of a target cabin air temperature at a specific time of day.
 14. The method of claim 8, wherein the request to precondition cabin air is triggered by a wireless device.
 15. A vehicle comprising: an engine and a battery, each configured to power a climate control system; and a controller programmed to, responsive to a command to precondition cabin air and an estimated battery state of charge, that would result from operating the climate control system to achieve the precondition, being less than a threshold, start the engine to power the climate control system regardless of an initial battery state of charge, and responsive to the command and the estimated battery state of charge exceeding the threshold, power the climate control system via the battery while the engine remains shutdown.
 16. The vehicle of claim 15, wherein the estimated battery state of charge is based on an estimated energy output required to power the climate control system to adjust a cabin air temperature from an initial temperature to a target temperature.
 17. The vehicle of claim 16, wherein the estimated energy output is adjusted to compensate for thermal losses to ambient surroundings.
 18. The vehicle of claim 15 further comprising an electrical connector configured to mate with and receive electrical power from a charging station to recharge the battery, and wherein the estimated battery state of charge is adjusted based on a battery charging condition.
 19. The vehicle of claim 15, wherein the command to precondition cabin air is triggered by a user presetting of a target cabin air temperature at a specific time of day.
 20. The vehicle of claim 15, wherein the command to precondition cabin air is triggered by a wireless device. 